Ultraviolet‐curing behavior and mechanical properties of a polyester acrylate resin

Ultraviolet (UV) curing technology has been widely used in many applications because it has several distinct advantages compared to solvent‐based processes or thermal‐curing technology. The effects of photoinitiator types and their contents as well as reactive diluent types and their contents on the UV‐curing behavior and mechanical properties of a UV‐curable polyester acrylate resin were investigated in this study. Three photoinitiators, Irgacure 184, Darocur 1173, and benzophenone, were used in this study. Hexanediol diacrylate, tripropylene glycol diacrylate, and trimethylol propane triacrylate were used as reactive diluents to modify the properties of the acrylate resin. The change of chemical structure during UV curing was monitored by FTIR. A universal testing machine was used to measure the tensile properties of various UV‐cured acrylate films of different compositions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3921–3928, 2004     

UV固化水性环氧树脂的合成研究

对紫外光固化水性环氧树脂的合成工艺进行了研究,讨论了反应温度、反应时间、催化剂种类和用量,阻聚剂、羧基含量及固含量、中和剂等对水性环氧丙烯酸酯的合成和性能的影响。结果表明,合成环氧丙烯酸酯的最佳反应温度110℃,环氧丙烯酸酯与马来酸酐的最佳反应反应温度为80℃。反应时间均为5 h,三乙胺作催化剂,用量为反应物总质量的0.5%,对羟基苯甲醚作阻聚剂。实验表明,提出的紫外光固化水性环氧树脂的合成工艺可行,合成树脂具有水性特征,性能指标可以满足应用要求。     

Synthesis of rosin‐based imidoamine‐type curing agents and curing behavior with epoxy resin

Rosin is an abundantly available natural product. The characteristic fused ring structure of rosin acids is analogous to that of some aromatic compounds in rigidity, and makes rosin and its derivatives potential substitutes for those aromatic compounds. In the study reported, the synthesis of biobased curing agents containing imide structure using rosin and the cure reaction were investigated. Rosin‐based imidoamine‐type curing agents were synthesized, and the chemical structure was confirmed using ¹H NMR, Fourier transform infrared and electrospray ionization spectroscopy. The curing behavior with diglycidyl ether of bisphenol A epoxy was studied using differential scanning calorimetry. The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis and thermogravimetry, respectively. The results indicate that the curing behavior of the rosin‐based curing agents is similar to that of curing agents with analogous structures. Cured products have good thermal stability due to the presence of the imide group and the bulky hydrogenated phenanthrene ring structure. Rosin acids have a great potential in the synthesis of epoxy curing agents as replacements for some of the current commercial aromatic or cycloaliphatic analogues. Copyright © 2010 Society of Chemical Industry     

Effects of composition of hardener on the curing and aging for an epoxy resin system

Different mixture ratios of Shell Epon 828 (based on diglycidyl ether of bisphenol A, DGEBA) and Shell EPI‐CURE 3046 (based on triethylenetetramine, TETA) were evaluated under different environments of isothermal curing at 80°C in DSC, room temperature curing in air, and aging in water at 45°C. The curing reactions were monitored using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), and infrared spectroscopy (IR). It was shown that the initial curing rate increased with the amount of hardener. However, the epoxy groups in samples with excess hardener were prone to reaction with primary amines located at the ends of TETA molecules, resulting in a less dense epoxy network. During aging in water at 45°C, significant effects of water on the postcure and the increased water absorption with an increase of hardener amount were observed. The DMA results show that the samples with hardener around stoichiometric composition have the greatest storage modulus while curing in air environment. However, the samples with hardener much less than stoichiometric composition have greater storage modulus under aging in water at 45°C. in water at 45°C. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 580–588, 2006     

Cationic UV‐curing of epoxidized cardanol derivatives

This paper demonstrates the high reactivity and potentiality of bio‐renewably obtained cardanol‐based epoxy monomers as well as the possibility of tuning the final thermomechanical properties by changing either the epoxy content or the chemical structure of the starting photocurable resin. The reactivity of the cardanol monomers towards the cationic UV‐curing process was investigated by Fourier transform IR analysis and it was shown that a high epoxy group conversion was achieved. Furthermore, the thermomechanical properties were investigated on crosslinked films by means of DSC and dynamic thermomechanical analysis. © 2020 Society of Chemical Industry     

Aging behavior of a hot‐cured epoxy system

The thermal and hydro‐thermal aging of a hot‐cured epoxy system (diglycidylether of bisphenol A (DGEBA) + dicyandiamide (DDA)) in the glassy state is revisited using DSC and IR attenuated total reflection spectroscopy. Because of the diffusion of DDA from the solid particles into the liquid DGEBA matrix, curing produces a highly crosslinked amorphous matrix that contains low crosslinked amorphous regions. After full curing, the network possesses a relatively low molecular mobility and no residual reactive groups. Thermal and hydro‐thermal loading is performed at 60°C, well below the principal glass transition temperature (T_g1 = 171°C). Both aging regimes cause significant chemical and structural changes to the glassy epoxy. It undergoes a phase separation of relatively mobile segments inside the low mobile matrix, providing a second glass transition that shifts from T_g2 = 86–114°C within 108 days of aging. This phase separation is reversible on heating into the viscoelastic state. Hydro‐thermal aging leads to a reversible and a nonreversible plasticizing effect as well. On thermal aging, no chemical changes are observed but hydro‐thermal aging causes significant chemical modifications in the epoxy system. These modifications are identified as a partial degradation of crosslinks produced by the cyano groups of the DDA and correspond to the nonreversible plasticitation. These changes in the cured epoxy should exert an influence on the mechanical properties of an adhesive bond. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Curing and post‐curing luminescence in an epoxy resin

A spontaneous luminescence is reported when epoxy resin samples are heated in air. This phenomenon is very sensitive to the nature of the atmosphere. The same treatment in nitrogen leads to an extinction of the luminescence. The emission process is restored when samples are kept for a sufficient time in air. To better understand this phenomenon, we have investigated the luminescence of the elementary constituents of the epoxy (resin and hardener), when heated in air and nitrogen, as well as during resin‐curing in the same atmospheres. It appears that the emission process is linked with the presence of oxygen. Although the kinetics of the luminescence can differ, depending on the nature of the sample (cured resin, resin during curing, liquid components), the emission spectra are the same during resin‐curing and upon heating of the cured resin and hardener. The emission spectrum of the base resin is different. It is concluded that the light results from a chemiluminescence process during oxidation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1899–1904, 2006     

Novel microencapsulated curing accelerator for prolonging shelf life of epoxy resin composition

A novel micron‐sized microencapsulated curing accelerator, imidazole (Im), particles, was first prepared by an ultrasound‐assisted dispersing and spray‐drying method and can significantly prolong the shelf life of epoxy resin‐based microelectronic packaging material. The shell of the encapsulated particles was made from ladderlike copoly(phenyloctyl silsesquioxane) (Ph‐Oct‐T), which was synthesized by a “stepwise coupling polymerization” method. Its softening or flowing temperature can be adjusted by changing the composition. Carbon tetrachloride (CCl₄) was chosen as both a solvent of the capsular material Ph‐Oct‐T and a suspending/precipitating agent of the fine Im particles. Subsequently, the solution containing Ph‐Oct‐T and suspended Im particles was treated by a spray‐drying process to produce the microencapsulated curing accelerator, Im particles, whose size and appearance was observed by scanning electronic microscopy (SEM). A greatly improved shelf life of the epoxy resin composition containing this microencapsulated curing accelerator was exhibited by curing tests and DSC measurements. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 873–878, 2002     

Initiator‐free photopolymerization of common acrylate monomers with 254 nm light

Using an available light source at a wavelength of 254 nm, common acrylate monomers were polymerized without any photoinitiators, which was confirmed using Fourier transform IR (FTIR) spectroscopy, ¹H NMR, gel permeation chromatography and fast atom bombardment mass spectrometric measurements. It was found that phenyl acrylate shows higher conversion than n‐ and t‐butyl acrylates. A trifunctional acrylate was also used for UV curing. The cured films were fabricated successfully on different kinds of substrates by using a batch‐ or conveyor‐type irradiation apparatus. It is indicated from FTIR spectral measurements that ca 40%–50% of acryloyl groups are consumed by the photopolymerization. Oxygen concentration in the sample chamber influences the photopolymerization, indicating that the polymerization proceeds via a radical process. © 2018 Society of Chemical Industry     

Synthesis and characterization of emulsion‐type curing agent of water‐borne epoxy resin

Self‐emulsified water‐borne epoxy curing agent of nonionic type was prepared using triethylene tetramine (TETA) and derivative of epoxy resin as a capping agent, which was synthesized by liquid epoxy resin (E51) and polyethylene glycol (PEG), and the curing agent possessed emulsification and curing properties at the same time. The curing agent with good property of emulsifying liquid epoxy resin could be obtained under the condition of the molar ratio of PEG : E51 : TETA as 0.8 : 1 : 3.5 at 80°C for 5 h. The mean particle size of the emulsion liquid was about 220 nm with the prepared curing agent and epoxy resin at the mass ratio of 1 : 3. The structure of the emulsion‐type curing agent was confirmed by FTIR and ¹H NMR spectra, and the mechanism of cured film formation was also analyzed by SEM photographs. The cured film prepared by the emulsion‐type curing agent and epoxy resin under ambient cure conditions showed good properties even at high staving temperature. This study provides useful suggestions for the application of the water‐borne epoxy resins in coating industry. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2652–2659, 2013     

UV curable soybean‐oil hybrid systems based on thiol‐acrylate and thiol‐ene‐acrylate chemistry

In this study, epoxidized soybean oil was modified to prepare acrylated epoxidized soybean oil (AESO) and vinyl/acrylate ended soybean oil (VASO), which were blended with mercaptopropyl polyhedral oligomericsilsequioxane (POSS‐SH) to prepare UV curable thiol‐acrylate and thiol‐ene‐acrylate hybrid coatings. Photopolymerization processes of the coatings were measured and the results showed that addition of POSS‐SH obviously increased the conversion of double bond. The physical and mechanical properties of all cured samples were investigated, which indicated that the pencil hardness, tensile strength, and fracture toughness were significantly improved by POSS‐SH. Moreover, with increasing POSS‐SH content, the water contact angles of cured samples were increased, and the water resistance was greatly improved. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42095.     

紫外光固化环氧丙烯酸树脂的合成

环氧丙烯酸（ＥＡ）树脂在辐射固化领域中是一种重要的感光树脂,其中双酚Ａ型环氧树脂的应用最为广泛。本文着重研究了该种树脂的合成工艺,讨论了原料投料比、反应温度、催化剂及操作方法等因素对树脂性能的影响,并通过正交试验确定了最佳反应条件。     

Hybridization of aqueous PU/epoxy resin via a dual self‐curing process

Amino‐terminated and carboxyl‐containing polyurethane (PU) is prepared by an isocyanate‐terminated PU prepolymer process. Carboxyl‐containing epoxy resin is obtained from a half‐esterification of epoxy resin with maleic anhydride. These two aqueous resins are obtained after neutralization with triethylamine and dispersion into water phase, respectively. A latent curing agent (TMPTA‐AZ) is prepared by a Michael addition of aziridine with trimethylolpropane triacrylate (TMPTA). A self‐curing system of PU/epoxy hybrid is obtained from a blending of these two aqueous resins with latent curing agent. PU/epoxy hybrid is derived from two self‐curing reactions on drying. The first curing for hybridization between PU amino groups with oxirane groups of epoxy resin is via a ring‐opening reaction and the secondary curing takes place on carboxyl groups of PU/epoxy hybrid with aziridine of TMPTA‐AZ. The final properties of these dual self‐cured PU/epoxy hybrids are reported. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

紫外光固化环氧丙烯酸酯涂料的表征

研制了一种用于艺术玻璃彩绘的新型涂料——紫外线固化环氧丙烯酸酯涂料，主要通过涂膜硬度的测定、红外光谱(FTIR)和差示扫描量热分析法(DSC)研究了涂膜固化程度与辐射时间之间的关系，并用紫外光谱和红外光谱研究了引发剂及其引发涂膜固化的机理。     

Studies on curing kinetics and thermal behavior of phosphorylated epoxy resin in the presence of aromatic amide‐amines

This article describes the synthesis of some novel aromatic amide‐amine curing agents by reacting 1 mole of p‐amino benzoic acid with 1 mole of each of 1,4‐phenylene diamine (P), 1,5‐diamino naphthalene (N), 4,4′‐(9‐fluorenyllidene)‐dianiline (F), 3,4′‐oxydianiline (O), and 4,4′‐diaminodiphenyl sulphide (DS) and were designated as PA, NA, FA, OA, and SA, respectively. The aromatic amide‐amines so synthesized were characterized with the help of spectroscopic techniques, viz., Fourier Transform Infrared, proton nuclear magnetic resonance, and carbon nuclear magnetic resonance. The curing kinetics of the epoxy resins obtained by reacting amines with diglycidyl ether of bisphenol‐A blended with tris(glycidyloxy)phosphine oxide in a ratio of 3 : 2, respectively, were investigated by DSC technique using multiple heating rate method (5, 10, 15, 20°C/min). Activation energies were determined by fitting the experimental data into Kissinger and Flynn‐Wall‐Ozawa Kinetic models. The activation energies obtained through Flynn‐Wall‐Ozawa method were slightly higher than Kissinger method but were comparable. However, both the energies were found to be dependent on the structure of amines. The thermal stability and weight loss behavior of isothermally cured thermosets were also investigated using thermogravimetric analysis in nitrogen atmosphere. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

环氧树脂固化促进剂的研究

以甲苯二异氰酸酯(TDI)和3-二甲氨基丙胺为单体、甲苯为溶剂,合成了环氧树脂(EP)的固化促进剂——甲苯-2,4-二(N,N′-二甲氨基丙脲)。为了验证自制促进剂的性能,以EP/双氰胺/促进剂为基体,并辅以填料、增韧剂、沉淀硫酸钡和流平剂等助剂,制备了粉末涂料。结果表明:制备促进剂的最佳工艺条件为n(TDI)∶n(3-二甲氨基丙胺)=1∶1.8、3-二甲氨基丙胺/甲苯溶液的滴加时间为1.5 h;当w(促进剂)=2.0%、固化温度为160℃时,粉末涂料的固化时间为6.5 min、胶化时间约100 s,并且其硬度、附着力和柔韧性俱佳,完全满足生产要求和使用要求。     

Curing behavior and thermal property of epoxy resin with boron‐containing phenol‐formaldehyde resin

The curing reaction of bisphenol‐A epoxy resin (BPAER) with boron‐containing phenol–formaldehyde resin (BPFR) was studied by isothermal and dynamic differential scanning calorimetry (DSC). The kinetic reaction mechanism in the isothermal reaction of BPAER‐BPFR was shown to follow autocatalytic kinetics. The activation energy in the dynamic cure reaction was derived. The influence of the composition of BPAER and BPFR on the reaction was evaluated. In addition, the glass transition temperatures (T_gs) were measured for the BPAER‐BPFR samples cured partially at isothermal temperatures. With the curing conditions varying, different glass transition behaviors were observed. By monitoring the variation in these T_gs, the curing process and the thermal property of BPAER–BPFR are clearly illustrated. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1054–1061, 2000     

Toughening of epoxy resin using acrylate‐based liquid rubbers

Carboxyl‐terminated poly(2‐ethylhexyl acrylate) (CTPEHA) liquid rubbers of different molecular weights and functionalities (LR‐1 to LR‐6) were synthesized by bulk and solution polymerization techniques. The liquid rubbers were characterized by nonaqueous titration, vapor pressure osmometry, and gel permeation chromatography. The CTPEHA oligomers were prereacted with the epoxy resin, and the modified epoxy networks were made by curing with an ambient‐temperature curing agent. The impact properties of the modified epoxy networks were evaluated, and the effects of molecular weight, functionality of the liquid rubber, and ductility of the matrix on the impact strength of the modified networks were investigated. The morphology of the toughening behavior was analyzed using a scanning electron microscope. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 716–723, 2000     

光固化低黏度环氧丙烯酸酯的合成与性能研究

合成了可紫外光固化的低黏度环氧丙烯酸酯树脂,通过红外光谱、核磁共振氢谱、碳谱对树脂结构进行了表征;采用综合热分析仪(DSC-TG)对树脂固化膜的耐热性能进行了分析。结果表明,在树脂中添加活性单体时,随单体官能度的增加,固化膜的耐热性能增加,但双官能团单体的用量对固化膜的耐热性能没有明显影响。固化膜具有较好的耐热性,初始分解温度为330.7℃,玻璃化转变温度为76.9℃。所得树脂黏度仅为3~4Pa.s(60℃),为市售产品的1/3,附着力1级,硬度4 H,耐水性能优异,无需添加单体使用。     

Effect of microencapsulated curing agents on the curing behavior for diglycidyl ether of bisphenol A epoxy resin systems

Microcapsules containing a curing agent, 2‐phenyl imidazole (2PZ), for a diglycidyl ether of bisphenol A (DGEBA) epoxy resin were prepared by a solid‐in‐oil‐in‐water emulsion solvent evaporation technique with poly(methyl methacrylate) (PMMA) as a polymeric wall. The mean particle size of the microcapsules and the concentration of 2PZ were about 10 μm and nearly 10 wt %, respectively. The onset cure temperature and peak temperature of the DGEBA/2PZ–PMMA microcapsule system appeared to increase by nearly 30 and 10°C, respectively, versus those of the DGEBA/2PZ system because of the increased reaction energy of curing. The former could take more than 3 months at room temperature, whereas the latter was cured after only a week. The values of the reaction order (a curing kinetic parameter) for DGEBA/2PZ and DGEBA/2PZ–PMMA microcapsules were quite close, and this showed that the curing reactions of the two samples proceeded conformably. The curing mechanism was investigated, and a two‐step initiation mechanism was considered: the first was assigned to adduct formation, whereas the second was due to alkoxide‐initiated polymerization. The glass‐transition temperature of DGEBA/2PZ was 165.2°C, nearly 20°C higher than the glass‐transition temperatures of DGEBA/2PZ–PMMA microcapsules and DGEBA/2PZ/PMMA microspheres, as determined by differential scanning calorimetry measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008